1. Field of the Invention
The trajectory adaptive safety-arming device disclosed herein pertains to mechanical devices which will maintain a guided missile warhead in an unarmed condition during all handling, storage, and aircraft flight conditions, but will arm the missile after it has been launched and a minimum separation distance has occured between the missile and the launching aircraft. Arming of the missile constitutes mechanical alignment of the most sensitive explosive elements (detonators) with the explosive train which leads to the high explosive warhead, and closing electrical switches between the firing circuit and detonators. More particularly, this safety-arming device utilizes lateral acceleration sensors and digital electronic circuitry to take lateral acceleration into account and thereby prevent arming of the missile before it has achieved a minimum separation distance because of steep turning maneuvers executed immediately after launch.
2. Description of the Prior Art
Current guided missile safety-arming devices measure either a fixed time interval or approximate distance from launch before arming. These two methods have been sufficient to insure that the missile was a safe distance away from the launch aircraft as long as the missile flew nearly straight ahead during the initial part of its flight. However, future missiles will have the ability to execute highly curved trajectories shortly after launch. Such a trajectory results in very high lateral acceleration levels being applied to the missile and its safety-arming device. Furthermore, future missiles are going to be required to engage enemy aircraft at close ranges. Therefore, the guided missile safety-arming device must provide for adequate separation from the launch aircraft before arming, but it must not limit the minimum launch range.
In order to meet this criteria, there must be a very accurate variable point at which arming will occur. Also, the safe separation point where warhead detonation will not cause unacceptable damage to the launch aircraft is a complex function of the relative positions, velocities, and orientations of the missile and launch aircraft. Therefore, the safe separation point is different for each type of trajectory flown. The safety arming device must be able to sense the type of trajectory which the missile is flying and adjust its arming point accordingly.
Previous safety-arming devices, which are predominately mechanical, are unacceptable in a missile which may undergo extreme lateral acceleration because these devices only integrate missile longitudinal acceleration which will result in an incorrect computation of missile separation distance and therefore possible early arming. The device described in this disclosure provides for (1) variable arming points, (2) sufficient accuracy to hit the "window" between the safe separation range and minimum target encounter range, and (3) operation under the severe lateral acceleration environments which are expected in highly maneuverable missiles.